Background. Since the introduction of endoscopic techniques in thyroid surgery, several trials of endoscopic lateral neck dissection have been conducted with the aim of avoiding a long cervical scar, but these endoscopic procedures require more effort than open surgery, mainly because of the relatively nonsophisticated instruments used. However; the recent introduction of surgical robotic systems has. simplified the operations and increased the precision of endoscopic techniques. We have described our initial experience with robot-assisted modified radical neck dissection (MRND) in thyroid cancer using the da Vinci S system. Methods. From October 2007 to October 2009, 33 patients with thyroid cancer with lateral neck lymph node (LN) metastases underwent robot-assisted thyroidectomy and additional robotic MRND using a gasless, transaxillary approach. Clinicopathologic data were analyzed retrospectively. Results. Mean patient age was 37 +/- 9 years and the gender ratio (male to female) was 7:26. The mean operating time was 281 +/- 41 minutes and mean postoperative hospital stay was 5.4 +/- 1.6 days. The mean tumor size was 1.1 +/- 0.5 cm and 20 cases (61%) had papillary thyroid microcarcinoma. The mean number of retrieved LNs was 6.1 +/- 4.4 in the central neck compartment and 27.7 +/- 11.0 in the lateral compartment. No serious postoperative complications, such as Homer's syndrome or major nerve injury, occurred. Conclusion. Robot-assisted MRND is technically feasible, safe, and produces excellent cosmetic results. Based on our initial experience, robot-assisted MRND should be viewed as an acceptable alternative. method in patients with low-risk, well-differentiated thyroid cancer with lateral neck node metastasis. (Surgery 2010;148:1214-21.)